Abstract Number: OC 63.4
Meeting: ISTH 2022 Congress
Theme: Hemophilia and Rare Bleeding Disorders » Hemophilia - Clinical
Background: Measurements of coagulation factor activity are essential for hemophilia management and are generally performed with the one-stage or chromogenic assay. Currently it is suggested that around one-third of patients with non-severe hemophilia A have assay discrepancy. These data are limited for non-severe hemophilia B. Knowledge on the extent of assay discrepancy in perspective of previous literature may facilitate further interpretation of this phenomenon.
Aims: To investigate the extent of assay discrepancy in moderate and mild hemophilia A and B.
Methods: Patients with non-severe hemophilia A and B were included from the multicenter international DYNAMO study. Central measurements of FVIII and FIX activity levels were performed by the one-stage (Actin FS reagents) and chromogenic assay (FVIII Siemens, FIX Rossix). Assay discrepancy was defined as a ratio >2.0 or < 0.5 between the assay results according to the SSC ISTH. Ethics approval and written consent was obtained (ClinicalTrials.gov: NCT03623295).
Results: A total of 221 patients were included of whom 4 patients (2%) showed assay discrepancy. This corresponded to 2/175 hemophilia A patients and 2/46 hemophilia B patients. Another 4 patients did not meet the criteria but exhibited a potential clinically relevant absolute difference >10 IU/dL between the assay results. The median difference between the assays was generally low with 1.1 IU/dL (IQR 0.5-2.1) for the total cohort, 1.0 IU/dL (IQR 0.4-1.9) in case of higher one-stage results and 1.3 IU/dL (IQR 0.7-2.4) in case of higher chromogenic results (Figure 1). Thirteen patients in this cohort had a F8/F9 mutation associated with assay discrepancy in at least 3 patients in previous literature. Most of these patients (92%) had no discrepant results in our study.
Conclusion(s): Little assay discrepancy was observed, even in those persons with mutations previously associated with discrepancy. This suggests that the previously reported discrepancy could be more dependent on laboratory- than on patient-related factors.
Figure 1
Scatterplot of centrally measured factor activity with one-stage vs. chromogenic assay. The colored dots represent patients with assay discrepancy -red dots- or patients that did not meet these criteria but had an absolute difference >10 IU/dL between the assay results -yellow dots-. The line reflects x=y.
To cite this abstract in AMA style:
Zwagemaker A, Kloosterman F, Gouw S, Boyce S, Brons P, Cnossen M, Collins P, Eikenboom J, Hay C, Jackson S, Kruip M, Laros-van Gorkom B, Male C, Nieuwenhuizen L, Shapiro S, Fijnvandraat K, Coppens M. Little discrepancy of one-stage and chromogenic assays in a large international cohort of patients with non-severe hemophilia A and B (DYNAMO study) [abstract]. https://abstracts.isth.org/abstract/little-discrepancy-of-one-stage-and-chromogenic-assays-in-a-large-international-cohort-of-patients-with-non-severe-hemophilia-a-and-b-dynamo-study/. Accessed September 22, 2023.« Back to ISTH 2022 Congress
ISTH Congress Abstracts - https://abstracts.isth.org/abstract/little-discrepancy-of-one-stage-and-chromogenic-assays-in-a-large-international-cohort-of-patients-with-non-severe-hemophilia-a-and-b-dynamo-study/